: : Someone who "has [or "gets"] cold feet" has sudden misgivings about a contemplated course of action and is likely to back out. I imagine the phrase comes from the effect of fear on one's circulatory system.

: : You're welcome.

: RE: Cold feet. I don't want to creep anybody out. But I was talking with an elderly relative about the days when most people died at home rather than in the hospital. She recalled as a young girl having to keep watch over her dying grandmother while her mother rested. Her mother instructed her that when grandmother's feet grew cold, the girl should come and get her mother because that was a signal that the old woman was near death. Makes you want to wear warm socks, doesn't it.

It makes sense, really. When a body is unable to keep every part of it warm (due to cold external temperatures or internal problems), it tries above all to keep the head and torso warm. It does this by diverting blood from the extremeties (hands, feet). People who exercise in cold weather often complain of cold feet and hands, and are often advised to make sure their heads are covered (most body heat escapes from the head!) I imagine cold feet on a critically ill person would indicate that the body is unable to keep itself warm, a very serious thing.